3.2 Volcanic Activity

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Vocabulary

Magma Chamber: A pocket in which magma collects.
Pipe: A long tube in the ground that connects the magma chamber to Earth's surface.
Lava Flow: The area covered by lava as it pours out of a vent.
Crater: A bowl- shaped area that may form at the top of a volcano around the volcano's central vent.
Silica: A material that is formed from the elements oxygen and silicon.
Pahoehoe: Fast-moving, hot lava.
Aa: Lava that is cooler and slower-moving.
Pyroclastic Flow: It occurs when an explosive eruption hurls out ash, cinders, and bombs as well as gases.
Active: Volcano is one that is erupting or has shown signs that it may erupt in the future.
Dormant: Volcano that is like a sleeping bear.
Extinct: Volcano that is unlikely to erupt again.
Hot Spring: A hot spirng forms when groundwater heated by a nearby body of magma rises to the surface and collects in a natural pool.
Geothermal Energy: In volcanic areas, heated by magma can provide a clean energy source called geothermal energy.

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Outline

How Magma reaches

• Magma rises
  • Dissolved gases in magma are under immense pressure
  • When a volcano erupts, it means that the gases have found a weak spot and have been released

Inside a Volcano

• Inside a volcano, there is a magma chamber
• There is a pipe which connects the chamber to the surface
• When a volcano erupts, you are seeing molten rock and gas leaving a vent

Characteristics of Magma

• Important Factors in an eruption
  • The amount of gas in the magma
  • How think or thin the magma is
  • Temperature of the magma
    • The hotter the magma, the more fluid it is
  • The silica content in the magma
    • The more silica in magma, the thicker it gets
  • Minerals that are formed by lava
    • Obsidian
      • formed when lava cools rapidly
    • Pumice
      • forms when gas bubbles are trapped inside the cooling magma

Types of Volcanic Eruptions

• Quiet Eruptions
  • When magma flows out easy, the volcanic eruption is quiet
    • Hawaii and Iceland were results of quiet eruptions
  • 2 different types of lava arre created through quiet eruptions
    • Pahoehoe
      • Fast moving hot lava
      • Land created by pahoehoe is like a potpourri of wrinkles,billows,and coils
    • Aa
      • Slower and cooler lava
      • When hardened, it has a rough surface containing jagged chunks of lava
• Explosive Eruptions
  • When the magma is thick and sticky, the results are an explosive eruption
    • The thick magma clogs up the hole and trapped gases can't escape until they explode, which result in the magma being forced out.

Stages of a Volcano

• A volcano may lay be active or dormant from a decade to 10,000,000 years
• An extinct volcano is one which can never erupt again

Other Types Of Volcanic Activity

• Two types of volcanic activity
  • Hot Spring
    • formed when magma heats groundwater and collects in a pool
  • Geyser
    • formed when hot water and steam are trapped and then comes up as a mixture
• In Reykjavik, Iceland, people rely on geothermal energy for warmth

Monitoring Volcanoes

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Geologists have more luck predicting volcanic eruptions than earthquakes

• Movement of magma into the magma chamber and through the pipe of the volcano trigger small earthquakes which help geologists find out if the volcano will erupt

Volcano Hazards

• Volcanic ash can bury towns, people, and damage crops